I am working on an ongoing project where I want to align the chain links so that it matches the contours of the Bezier curve. I am currently following these steps.
- Drawing a curve.
- Use the display list to create a single link in the chain.
- Use the FOR loop to repeatedly call a function that calculates the angle between two points of the curve, returns the angle and the axis around which the link should be rotated.
- Turn the corner "a" and move to a new position, place the link in a new position.
Edit: I must also say that the centers of two one-and-a-half tori must lie on the Bezier curve. I also know that the method that I use to draw the torus is tiring, later I will use TRIANGLE_FAN or QUAD_STRIP to draw the torus more efficiently.
While at first glance this logic looks like it displays the chain correctly, the final result is not what I imagined. Here's a picture of how the chain looks.

I read that before translating you need to translate the object to the origin? Would I just call glTranslate (0,0,0) and then follow step 4 from above?
I have included the appropriate code from what I have done so far, I would appreciate any suggestions that will help me work correctly with the code.
double getAxisAngle(pointType oldPoint[],
pointType newPoint[],pointType axisOfRot[]){
float tmpPoint[3];
float normA = 0.0,normB = 0.0,AB = 0.0,angle=0.0;
int i;
axisOfRot->x= oldPoint->y * newPoint->z - oldPoint->z * newPoint->y;
axisOfRot->y= oldPoint->z * newPoint->x - oldPoint->x * newPoint->z;
axisOfRot->z= oldPoint->x * newPoint->y - oldPoint->y * newPoint->x;
normA=sqrt(oldPoint->x * oldPoint->x + oldPoint->y * oldPoint->y + oldPoint->z *
oldPoint->z);
normB=sqrt(newPoint->x * newPoint->x + newPoint->y * newPoint->y + newPoint->z *
newPoint->z);
tmpPoint[0] = oldPoint->x * newPoint->x;
tmpPoint[1] = oldPoint->y * newPoint->y;
tmpPoint[2] = oldPoint->z * newPoint->z;
for(i=0;i<=2;i++)
AB+=tmpPoint[i];
AB /= (normA * normB);
return angle = (180/PI)*acos(AB);
}
void bezierInterpolation(float t,pointType cPoints[],
pointType newPoint[]){
newPoint->x = pow(1 - t, 3) * cPoints[0].x +3 * pow(1 - t , 2) * t * cPoints[1].x + 3
* pow(1 - t, 1) * pow(t, 2) * cPoints[2].x + pow(t, 3) * cPoints[3].x;
newPoint->y = pow(1 - t, 3) * cPoints[0].y +3 * pow(1 - t , 2) * t * cPoints[1].y + 3
* pow(1 - t, 1) * pow(t, 2) * cPoints[2].y + pow(t, 3) * cPoints[3].y;
newPoint->z = pow(1 - t, 3) * cPoints[0].z +3 * pow(1 - t , 2) * t * cPoints[1].z + 3
* pow(1 - t, 1) * pow(t, 2) * cPoints[2].z + pow(t, 3) * cPoints[3].z;
}
torusList=glGenLists(1);
glNewList(torusList,GL_COMPILE);
for (i=0; i<=180; i++)
{
degInRad = i*DEG2RAD;
glPushMatrix();
glTranslatef(cos(degInRad)*radius,sin(degInRad)*radius,0);
glRotated(90,1,0,0);
gluCylinder(quadric,Diameter/2,Diameter/2,Height/5,10,10);
glPopMatrix();
}
glEndList();
linkList = glGenLists(1);
glNewList(linkList, GL_COMPILE);
glPushMatrix();
glCallList(torusList);
glRotatef(90,1,0,0);
glTranslatef(radius,0,0);
gluCylinder(quadric, Diameter/2, Diameter/2, Height,10,10);
glTranslatef(-(radius*2),0,0);
gluCylinder(quadric, Diameter/2, Diameter/2, Height,10,10);
glTranslatef(radius,0, Height);
glRotatef(90,1,0,0);
glCallList(torusList);
glPopMatrix();
glEndList();
Finally, here is the code to create three links in the chain
t=0.031;
bezierInterpolation(t,cPoints,newPoint);
a=getAxisAngle(oldPoint,newPoint,axisOfRot);
glTranslatef(newPoint->x,newPoint->y,newPoint->z);
glRotatef(a,axisOfRot->x,axisOfRot->y,axisOfRot->z);
glCallList(DLid);
glRotatef(-a,axisOfRot->x,axisOfRot->y,axisOfRot->z);
glTranslatef(-newPoint->x,-newPoint->y,-newPoint->z);
oldPoint[0]=newPoint[0];
bezierInterpolation(t+=GAP,cPoints,newPoint);
a=getAxisAngle(oldPoint,newPoint,axisOfRot);
glTranslatef(newPoint->x,newPoint->y,newPoint->z);
glRotatef(90,0,1,0);
glRotatef(a,axisOfRot->x,axisOfRot->y,axisOfRot->z);
glCallList(DLid);
glRotatef(-a,axisOfRot->x,axisOfRot->y,axisOfRot->z);
glRotatef(90,0,1,0);
glTranslatef(-newPoint->x,-newPoint->y,-newPoint->z);
oldPoint[0]=newPoint[0];
bezierInterpolation(t+=GAP,cPoints,newPoint);
a=getAxisAngle(oldPoint,newPoint,axisOfRot);
glTranslatef(newPoint->x,newPoint->y,newPoint->z);
glRotatef(-a,axisOfRot->x,axisOfRot->y,axisOfRot->z);
glCallList(DLid);
glRotatef(a,axisOfRot->x,axisOfRot->y,axisOfRot->z);
glTranslatef(-newPoint->x,-newPoint->y,newPoint->z);